Dry reed contact relay with permanent magnet



Dec. 31, 1968 M- BAERMANN 3,419,829

DRY REED coNTAcT RELAY WITH PERMANENT MAGNET Filed Dec. 2. 1960 ,a FIG.

INVENTOR MAX BAERMANN i BY m2o. ToRNEY United States Patent O 3,419,829 DRY REED CONTACT RELAY WITH PERMANENT MAGNET Max Baermann, Bensberg-Wulfshof, Bezirk, Cologne, Germany Filed Dec. 2, 1960, Ser. No. 73,236

Claims priority, applicatitnslGsermany, July 9, 1960,

s claims. (ci. 335-153) ABSTRACT 0F THE DISCLOSURE This invention pertains to the art of dry reed contact relays and more particularly to a dry reed contact relay having a permanent magnet associated therewith.

Dry reed contact -relays normally consist of a pair of contacts -contained in a sealed glass tube. These contacts are in the form of ilexible vanes of ferromagnetic materials and are so arranged as to be in overlapping nor-v mally spaced relationship. If these contacts are introduced into a magnetic eld, they are drawn together until they touch. Such a relay would be known as one having normally open contacts.

These relays can be changed into ones having normally closed contacts by premagnetizing the contacts with a permanent magnet. An electrically generated magnetic eld having a polarity opposite to the polarity of the permanent magnets cancels the magnetic effect of the magnet and the contacts then spring apart. With this last arrangement, the permanent magnet must be placed next to or on the contacts. The space required for such permanent magnets is space which could be employed for other contacts and is thus Wasted.

The present invention overcomes all of these disadvantages and others and prevents the wasting of the space normally required for the permanent magnets.

In addition, the present invention provides a dry reed contact which can be readily changed from normally open contact type to the normally closed contact type and vice versa.

In accordance with the present invention, one or a plurality of dry reed contacts comprised of magnetically permeable material are entirely or partially surrounded in spaced relationship by a permanent magnet material having low magnetic permeability and a high coercive eld strength. Other magnet means are then provided which cancel the magnetic eld of this magnet.

Thus, in accordance with one aspect of the invention, a pair of dry reed contacts are placed in a tube shaped permanent magnetic body which surrounds the contacts closely on all sides, or several dry reed contacts are so placed in a permanent magnetic body such that each one is surrounded by a permanent magnetic material for at least a fourth of its periphery. This can be done most advantageously in accordance with the invention if the dry reed contacts are disposed in a tube made of particles of permanent magnetic material dispersed in a binder ICC of insulating material. Such tube can then form the spool for the electromagnet.

Further in accordance with the invention, a permanent magnetic body, preferably in the form of a spool, is so selectively magnetized that only part of the dry reed `contacts lie adjacent to the magnetized portions and are magnetized so as to operate as normally closed contacts while the remaining dry reed contacts lie adjacent magnetized portions and work as normally open contacts.

Additionally in accordance with the invention, the degree of premagnetizing the dry reed contacts by the permanent magnetic field can be readily changed by orienting the contacts relative to the magnetized portions. Thus, the sensitivity of the relay can be readily adjusted.

Still further in accordance with the invention, the possibility of adjustment of the sensitivity can be further improved by an unsymmetrical magnetizing of the permanent magnet body such that one set of normally closed contacts can be arranged to be opened by energizing the electromagnet in one direction while another set of contacts can be provided in the same relay to open with a flow of current in the electromagnet in the opposite direction.

Such unsymmetrical magnetizing normally consists of magnetizing the inner surfaces of the permanent magnet body, that is, the surfaces facing the contacts, with opposite magnetic poles.

Further in accordance with the invention, supersensitive relays may be provided having a short circuit armature for the electromagnet, in which event the permanent magnetic body will be magnetized radially.

The principal object of the invention is the provision of a new and improved dry reed contact relay which may be of the normally closed contact type which occupies a minimum of space and for a given size of electromagnet can have a maximum number of sets of contacts.

Another object of the invention is the provision of a new and improved dry reed contact type of relay wherein the contacts may readily change from normally open to normally closed and vice versa.

Another object of the invention is the provision of a new and improved dry reed contact type of relay wherein the sensitivity may be readily adjusted.

Still another object of the invention is the provision of a new and improved dry reed contact relay wherein a plurality of contacts, either normally open or normally closed, or both, may be simultaneously operated by the same electromagnet.

Still another object of the invention is the provision of a new and improved dry reed contact relay which is simple in construction, relatively cheap to manufacture, and effective and positive in operation.

The invention may take form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawing which form a part hereof and wherein:

FIGURE l is an illustration of a dry reed contact relay illustrating a preferred embodiment of the invention;

FIGURE 2 is a view somewhat similar to FIGURE l but showing the electromagnet in position;

FIGURE 2a is a schematic view illustrating the polarity of the permanent magnet of FIGURE 2;

FIGURE 3 shows a still further embodiment of the invention;

FIGURE 4 shows a still further embodiment of the invention wherein a plurality of contacts are operated by the same electromagnet, the view being taken approximately inthe line 4 4 of FIGURE 5;

FIGURE 5 is a cross-sectional view taken `approximately on the line 5-5 of FIGURE 4;

FIGURE 6 is a perspective view with portions broken away for the purposes of clarity; and,

FIGURE 7 is a perspective view of apparatus suitable for magnetizing a permanent magnet body of FIGURES 1-6.

Referring now to the drawings which are for the purpose of illustrating an embodiment of the invention, and not for the pur-pose of limiting the same, FIGURE l illustrates a dry reed contact arrangement which includes a tube 10 sealed at its opposite ends. Although the tube is preferably fromed from glass, it may comprise any -magnetically non-permeable material. Extending into the sealed ends of tube 10 are a pair of dry reed contacts 12 and 14 each of ferromagnetic material and having overlapping ends as at 16 intermediate the ends of the tube. As will hereinafter Vbecome apparent, the contacts 12 and 14 have flat faces at 16 which face each other these dat faces of the contacts Kbeing best illustrated in FIGURE 6. Surrounding the tube 10 is a tubular permanent magnet 18 which may comprise permanently magnetic particles such as iron-barium-oxide dispersed within a plastic binder. The composition and characteristics of such a -magnet are fully described, for example, in my copending application, Ser. No. 693,603, tiled Oct. 3l, 1957, now Letters Patent No. 2,959,832.

A magnet of the type described in the aforesaid patent may be magnetized to have north and south poles at its opposite ends as shown in FIGURE 1. Thus, when the magnet 18 is magnetized in this manner, the resulting magnetic field will magnetize the ferromagnetic contacts 12 and 14, with contact 14 acting as a south pole while contact 12 acts as a north pole, the result being that the two contacts, formed from a spring material and normally spaced apart, are pulled together into engagement to -make electrical contact.

In FIGURE 2, another embodiment of the invention is shown which again includes a glass (or other magnetic non-permeable material) tube 20 having a pair of ferromagnetic dry reed contacts 22 and 24 extending into its opposite ends and overlapping as at 26. As was the case in FIGURE l, `a tubular permanent magnet 28 formed of permanently magnetic particles dispersed within a plastic binder surrounds the tube 20. In this latter case however, the magnet 28 is magnetized radially as shown in FIGURE 2a. That is, north and south poles are produced at opposite radial sides of the magnet as indicated in FIGURE 2a. Furthermore, it will be noted that the radial polarity is reversed at opposite axial ends of the magnet. The ends of the tubular magnet 28 are interconnected by a short circuit path consisting of a ferromagnetic shunting member 32 and the pole shoes 34 and 36. The radially magnetized permanent magnet 28 may comprise a single integral tubular member as shown, or it may comprise a pair of short tubular members one at each end of the tube 20, if desired. Each such magnet will be radially and axially magnetized the same as the single long magnet 28.

With the arrangement shown in FIGURES 2 and 2a, the contact 24 will comprise a south pole and the contact 22 will comprise a north pole. Consequently, the two contacts will repel each other and will be normally open. Surrounding the tubular magnet 28 is a coil 38 adapted to produce a magnetic eld having north and south poles at its opposite ends. The strength of this magnetic tiel-d will be such as to overcome the iield produced by magnet 28 and the contacts 22, 24 will be released from engagement. Thus, the assembly of FIGURE 2 comprises a pair of normally closed contacts which may be selectively opened by energizing the coil 38.

In FIGURE 3, an arrangement similar to FIGURE l is shown which comprises a glass or the like tube 40 having a pair of dry reed contacts 42 and 44 extending into its lopposite ends. A tubular permanent magnet 46 surrounds the tube 40 and is provided with radially-extending flanges 48 and 50 at its opposite ends. The flanges 48 and 50 serve to confine or support a coil 52. With this arrangement, assuming that the Imagnet 46 is magnetized to have north and south poles at its opposite ends, the contacts 42 and 44 will be normally pulled into engagement. These contacts, however, are spring-biased whereby they will pull apart in the 'absence of a magnetic eld. Thus, by energizing the coil 52 to produce a magnetic field opposing that produced by the permanent magnet 46, the effect of the magnetic field can be reduced to substantially zero and the contacts 42 and 44 will open.

Referring now to FIGURES 4, 5 and 6, the arrangement shown includes a plurality of parallel Iglass tubes 54, 56, 58 and 60, all enclosed within a generally tubular permanent magnet 62 having anges 64 and 66 at its opposite ends. A coil 68 surrounds the magnet 62, as shown, between the flanges 64 and 66.

It is a characteristic of a permanent magnet formed from iron-bari-um-oxide or the like embedded within a plastic binder that it -rnay be magnetized differently at various portions of its area. That is, the tubular member 62 may be magnetized to have axially opposite north and south poles adjacent glass tubes 58 and 56 while being unmagnetized adjacent the tubes 54 and 60. Consequently, as shown in FIGURE 5, the contacts within tubes 54 an-d 58 will be normally closed, while those within tubes 54 and 60 will be normally open. The tubular magnet 62 may be magnetized in sections by an arrangement such as that shown in FIGURE 7 which comprises a coil 70 having axially opposite pole pieces 72 and 74 at one point around its periphery. The coil may be connected, by means of leads 76 and 78, to capacitor discharge apparatus, the arrangement being such that the coil 70 may be inserted into the tubular member 62; and when the capacitor discharges, the magnetic lines of flux produced by the coil 70 will be concentrated at the .pole pieces 72 and 74 to axially magnetize the member 62 at one point only around its periphery, this point being adjacent the pole pieces.

Now, when the coil 68 surrounding magnet 62 is energized, the normally open contacts 54 and 60 will be closed, while the normally closed contacts within tubes 56 and 58 will be opened. Thus, the single signal applied to coil 68 serves to actuate four different sets of contacts simultaneously.

By virtue of the iiat faces of the contacts, they may be rotated within the tubular magnet 62 to vary the eiect of the magnetic field on the contacts. That is, by rotating the tube 54 or 60, for example, the number of magnetic lines of flux cutting through the contacts may be varied to vary the sensitivity of the device.

Although the invention has been shown in connection with certain specific embodiments, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit re quirements without departing from the spirit and scope of the invention.

Thus having described my invention, I claim:

1. In a magnetically operated switch, the combination of a protective tube having a pair of exible elongated contact members extending into its opposite ends, said contact members `having ends xed at the respective ends of the tube and relatively movable free ends which overlap within the tube inte-rmediate its ends, said 'contact members being formed from magnetically permeable material and being adapted to move from a closed position to an open position and vice versa, a cylindrical ermanent magnet surrounding said tube, said cylindrical permanent magnet comprising a hardenable binder with particles of high coercivity and low permeability permanent magnet material dispersed within and bonded together by said binder, said cylindrical magnet being magnetized in a radial direction to produce radial poles at the opposite ends of said magnet with the radial poles lying in a plane extending through the longitudinal axis of said tube, the radial poles at the opposite ends of the tube being reversed with respect to each other in said plane, a magnetic shunt interconnecting the ends of said permanent mag-net, and an electro-coil surrounding said cylindrical magnet and adapted to produce a magnetic field tending to canse the contact members to open.

2. A magnetically operated switch comprising a plurality of parallel elongated protective tubes positioned sideby-side, each of said tubes having a pair of flexible elongated contact members extending into its opposite ends, said contact members having ends fixed at the respective ends of their associated protective tube and relatively movable free ends which overlap within the tube intermediate its ends, said contact members being formed from magnetically permeable material, a generally tubular member surrounding said parallel tubes and formed from permanent magnetic particles having low permeability in the order of the permeability of ironbarinm oxide embedded within a plastic binder, the peripheral portions of said tubular member being magnetized adjacent certain ones of said protective tubes to produce north and south poles at the opposite ends of said peripheral portions and hold the contact members within the protective tubes adjacent said peripheral portions in closed position, the contact members within the protective tubes adjacent the unmagnetized peripheral portions of said tubular member remaining open, and an electro-coil surrounding said tubular member and adapted to produce a magnetic field opposing the magnetic field produced by the poles on said peripheral portions to open said normally closed contacts while closing said normally open contacts.

3. A magnetically operated switch comprising a plurality of parallel elongated protective tubes positioned sideby-side, each of said tubes having a pair of flexible elongated contact members extending into its opposite ends, said contact members being formed from magnetically permeable material, and a generally tubular member of magnetic material surrounding said parallel tubes, said magnetic material comprising a hardenable binder with particles of high coercivity and low permeability permanent magnet material dipersed within and bonded together by said binder, peripheral portions of said tubular member being magnetized adjacent certain ones of said tubes to produce north and south poles at the opposite ends of said peripheral portions and hold the contact members within the protective tubes adjacent said peripheral portions in closed position, the contact members within the protective tubes adjacent the unmagnetized peripheral portions of said tubular member remaining open.

4. In a magnetically operated switch, the combination of an elongated protective enclosure having a pair of flexible elongated flattened conta-ct members extending into its opposite ends with flat faces of the respective members facing each other, said contact members having ends fixed at the respective ends of the elongated enclosure and relatively movable free ends which overlap within the enclosure intermediate its ends, said contact members being formed from magnetically permeable material, and a generally tubular member surrounding said protective enclosure and being formed from permanently magnetic particles having low permeability embedded within a plastic binder, said tubular member being magnetized to have axially opposite magnetic poles on an arcuate portion of its periphery whereby the effect of a magnetic field produced on the flat contact members may be varied by rotating the Contact members with respect to said arcuate portion of the periphery of said tubular member, an electro-coil surrounding said tubular member and mounted thereto and adapted to produce a magnetic field opposed to the magnetic field produced by said tubular member.

5. A magnetically operated, normally closed switch, said switch comprising a protective tube having a pair of flexible elongated contact members extending into its opposite ends, said contact members having ends fixed at the respective ends of said tube and respectively movable free ends which overlap within the tube intermediate its ends, said contact members being formed from magnetically permeable material, and a cylindrical permanent magnet surrounding said tube and magnetized to have opposite magnetic poles with sufficient pole strength to close said members, said tube being formed from a nonmagnetically permeable material, said cylindrical permanent magnet being formed from a fine dispersion of permanently magnetic particles of low permeability ernbedded within a 4hardened plastic binder and an electrocoil mounted on said cylindrical permanent magnet and adapted to be energized to produce a magnetic effect on said members opposite from the magnetic effect of said permanent magnet on said members, said magnetic effect of said electro-coil being sufficient to open said member against the magnetic effect of said permanent magnet whereby the members open upon energization of said electro-coil and o'lose upon deenergization of said electrocoil.

References Cited UNITED STATES PATENTS 2,889,424 6/1959 Glore et a. 2,959,832 11/1960 Baermann 317-158 2,999,915 9/ 1961 Pfleiderer et al. 3,024,392 3/1962 Baermann 317-159 2,877,315 3/1959 Oliver. 2,902,558 9/ 1959 Peer.

FOREIGN PATENTS 1,186,645 8/1959 France.

BERNARD A. GILHEANY, Primary Examiner.

r ROY N. ENVALL, JR., Assistant Examiner. 

